Hey there @Ian_D, thank you for reaching out.
You can be charged for things such as going over your roaming allowance and using extra usages of calls, data or texts.
You can also be charged for connecting to the maritime network if you went out to/near the sea.
You can also be charged for going through another country not included in our EU package, or being near to and connecting to a country whose border you’re near whose not included in the EU package.
If you’d like further information on your actual charges, I’d recommend contacting us via our live-chat;
https://www.idmobile.co.uk/live-chat
Thanks,
Tyler